1. Field of the Invention
The present invention relates to a method and system for chemical-mechanical polishing, and, more particularly, to a method and system for tunable removal rates and selectivity during chemical-mechanical polishing.
2. Description of the Related Art
During semiconductor device fabrication, the planarity required at each level of a multilevel structure is often achieved using chemical-mechanical planarization (“CMP”). CMP typically uses a chemical solution or an abrasive and a chemical slurry to remove material. The abrasive scrapes the material to remove it, while the chemical slurry reacts with the material to weaken it for removal.
During the typical fabrication process for microelectromechanical systems (“MEMS”), integrated circuits, or through-silicon via structures, one or more top layers of silicon dioxide, silicon nitride and/or polysilicon/si(100) must be polished with a dispersion that yields a very high or low polysilicon/si(100) removal rate (“RR”) and a high or low selectivity over the underlying or overlying silicon dioxide, silicon nitride and/or copper layers. Both the removal rate of the undesired material and the selectivity for removal of the undesired material over the desired material are key metrics of the CMP process.
Accordingly, there is a continued need to achieve tunable removal rates and selectivities of materials commonly used in device fabrication, including but not limited to polysilicon/si(100), silicon dioxide, copper, and silicon nitride.